Bryant Bruant 4 Way Gas 355AAV - Manual (Page 56)

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BURNER FLAME
BURNER
MANIFOLD
A89020
Fig. 61 -- Burner Flame
Table 15 – Altitude Derate Multiplier for USA.
ALTITUDE
FT (M)
PERCENT OF
DERATE
DERATE MULTIPLIER
FACTOR*
0–2000
(0---610)
0 1.00
2001–3000
(610---914)
4---6 0.95
3001–4000
(914---1219)
6---8 0.93
4001–5000
(1219---1524)
8---10 0.91
5001–6000
1524---1829)
10---12 0.89
6001–7000
(1829---2134)
12---14 0.87
7001–8000
(2134---2438)
14---16 0.85
8001–9000
(2438---2743)
16---18 0.83
9001–10,000
(2743---3048)
18---20 0.81
* Derate multiplier factors are based on midpoint altitude for altitude range.
EXAMPLE: 100,000 BTUH HIGH--HEAT INPUT
FURNACE INSTALLED AT 4,300 FT. (1311 M)
Furnace Input Rate at Sea Level X Derate Multiplier Factor
= Furnace Input Rate at Installation Altitude
100,000
X 0.91 = 91,000
CANADA
At installation altitudes from 2000 to 4500 ft, (610 to 1372 M) this
furnace must be derated 5 percent by an authorized Gas
Conversion Station or Dealer. To determine correct input rate for
altitude, see example above and use 0.95 as derate multiplier factor.
b. Reinstall burner box cover.
NOTE: Clocking gas input rate MUST always be performed with
the burner box cover INSTALLED.
c. Check that gas valve adjustment caps are in place for
proper input to be clocked.
d. Obtain average heat value (at altitude) from local gas
supplier.
NOTE: Be sure heating value of gas used for calculations is
correct for your altitude. Consult local gas utility for altitude
adjustment of gas heating value.
e. Check and verify orifice size in furnace. NEVER
ASSUME THE ORIFICE SIZE. ALWAYS CHECK
AND VERIFY.
f. Turn off all other gas appliances and pilots.
g. Move setup switch SW1--2 to ON position. (See Fig.
37.) This keeps furnace locked in low--heat operation.
h. Jumper R to W/W1.
i. Let furnace run for 3 minutes in low--heat operation.
j. Measure time (in sec) for gas meter to complete 1
revolution. Note reading.
k. Refer to Table 16 for cubicft. of gas per hr.
l. Multiply gas rate cu ft./hr by heating value (Btu/cu ft.).
m. Move setup switch SW1--2 to OFF position and jumper
R and W/W1 and W2 thermostat connections. (See Fig.
37.) This keeps furnace locked in high--heat operation.
Repeat items i through l for high--heat operation.
EXAMPLE: (High--heat operation at 0--2000ft. (0--610 M)
altitude)
Furnace input from rating plate is 100,000 Btuh
Btu heating input = Btu/cuft. X cu ft./hr
Heating value of gas = 975 Btu/cu ft.
Time for 1 revolution of 2--cu ft. dial = 70 sec
Gas rate = 103 cu ft./hr (from Table 16)
Btu heating input = 103 X 975 = 100,425 Btuh In this
example, the orifice size and manifold pressure adjustment
is within +/--2 percent of the furnace input rate.
NOTE: Measured gas inputs (high heat and low heat) must be
within +/--2 percent of that stated on furnace rating plate when
installed at sea level or derated per that stated above when installed
at higher altitudes.
n. Remove jumper across R, W/W1, and W2 thermostat
connections to terminate call for heat.
355A